section name header

Introduction ⬇

Haptoglobin (Hp) is a transport glycoprotein synthesized solely in the liver. It is a carrier for free Hb in plasma; its primary physiologic function is the preservation of iron. Hp binds Hb and carries it to the reticuloendothelial system.

A decrease in Hp (with normal liver function) is most likely to occur with increased consumption of Hp due to intravascular hemolysis. The concentration of Hp is inversely related to the degree of hemolysis and to the duration of the hemolytic episode.

Normal Findings ⬆ ⬇

Newborns: 5–48 mg/dL or 50–480 mg/L (may be absent at birth)

Children: reach adult levels by 1 year

Adults: 40–200 mg/dL or 0.4–2.0 g/L

Procedure ⬆ ⬇

  1. Obtain a venous blood sample of at least 2 mL (red-topped tube or SST). Label the specimen with the patient’s name, date and time of collection, and test(s) ordered. Place the specimen in a biohazard bag.

  2. Measure the serum for Hp by a radial immunodiffusion method. A single determination is of limited value.

Clinical Implications ⬆ ⬇

  1. Hp is decreased in acquired disorders such as:

    1. Intravascular hemolysis from any cause

    2. Autoimmune hemolytic anemia

    3. Other hemoglobinemias caused by intravascular hemorrhages, especially artificial heart valves, and acute bacterial endocarditis

    4. Transfusion reactions

    5. Erythroblastosis fetalis

    6. Malarial infestation

    7. PNH

    8. Hematoma, tissue hemorrhage

    9. Thrombotic thrombocytopenic purpura

    10. Drug-induced hemolytic anemia (methyldopa)

    11. Acute or chronic liver disease

  2. Hp is decreased in some inherited disorders such as:

    1. Sickle cell disease

    2. G-6-PD and PK deficiency

    3. Hereditary spherocytosis

    4. Thalassemia and megaloblastic anemias

    5. Congenital absence is observed in 1% of African American and Asian populations

  3. Hp is increased in:

    1. Infection and inflammation (acute or chronic)

    2. Neoplasias, lymphomas (advanced)

    3. Biliary obstruction

    4. Acute rheumatic disease and other collagen diseases

    5. Tissue destruction

Interventions ⬆ ⬇

Pretest Patient Care

  1. Advise patient of test purpose.

  2. Avoid use of oral contraceptives and androgens before blood is drawn. (Check with the healthcare provider.)

  3. Avoid exercise before test.

  4. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Posttest Patient Care

  1. Have the patient resume normal activities and medications.

  2. Review test results; report and record findings. Modify the nursing care plan as needed. Counsel the patient regarding abnormal findings; explain the need for possible follow-up testing and treatment. Monitor for abnormal bleeding.

  3. Follow guidelines in Chapter 1 for safe, effective, informed posttest care.

Interfering Factors ⬆

  1. Estrogen and oral contraceptives lower Hp.

  2. Steroid therapy raises Hp.

  3. Androgens increase Hp.

  4. Regular strenuous exercise lowers Hp.

Normal Hp results measured during inflammatory episodes or during steroid treatment do not rule out hemolysis.